(A) Field of the Invention
The present invention relates to a balloon for medical tubes and a medical tube equipped with such a balloon. More specifically, the present invention pertains to a balloon for medical tubes, which has variable bendability, which can impart, to a medical tube to be inserted into a living body for examinations and/or treatments, a direction-selecting function (the ability to select the course or direction of the tip of the medical tube) due to the variable or arbitrary bendability of the balloon or can impart, to the medical tube, a function of separating tissues by the variable bending motions of the balloon, while making the most use of the difference in the partial stretchability of the balloon induced when a pressurized fluid is injected therein, as well as a medical tube equipped with such a balloon.
(b) Description of the Prior Art
Operations performed in the past requiring severe operative invasion has gradually been superseded by the operative techniques with less operative invasion. For instance, there have been spread widely therapeutic methods with minimum invasion therapy (MIT), mainly based on techniques which make use of catheters and endoscopes, such as PTCA, PTA and stent techniques, atelectomy, embolization and operations performed under an endoscope.
In particular, in the field of the catheter techniques, there have been developed a variety of balloon-catheters in order to, for instance, supply a medical fluid or an infusion solution to a specific site in a body cavity such as a blood vessel, a digestive tract, a uterine tube or a ureter, or to expand a site with a stenosis by the expansive force of a balloon.
However, a higher operative technique will require the development of a catheter whose tip portion has an ability to select its course of advancement by the bending of the same. In respect of the bending mechanism of the tip of a catheter, various structures have been proposed, but they are all complicated and the diameter of the catheters would inevitably be increased.
In addition, a catheter has conventionally been used only for the body cavities, except for a part of operations performed under endoscopes. However, there has been desired for the development of a catheter technique which is not limited only to the transluminal approach techniques which make use of biological tracts and/or cavities such as blood vessels, as the area of catheter application is widely expanded.
A cavity should be formed within a variety of tissues by a less frictional means to treat a target site by letting a catheter arrive at a desired site from the exterior of a biological tract or cavity, unlike the technique which makes use of the biological tract or cavity. To this end, tissues should often be separated over a wide area. After the catheter arrives at the desired portion, various tools may be adapted to carry out diagnosis and/or treatments through the use of the multiple lumens of the catheter.
As a method for separating tissues, the tip of a catheter may continuously be deformed and moved after the catheter arrives at the desired site on the tissue to be separated. Various structures have been proposed, as the bending mechanisms of the tip of the catheter, but all of them are very complicated and the diameter of the catheters would inevitably be increased. Moreover, there has not yet been developed any multifunctional catheter designed from the viewpoint of the non-transluminal approach to the tissue separation from the outside of the biological tract or cavity.